The primary goal of the Tumor Immunology section of the Surgery Branch is to develop new immune-based therapies to treat patients with cancer. The Antigen Targeting Core facility was developed to assist Surgery Branch investigators in the identification of antigenic tumor associated epitopes and in raising tumor reactive T cell populations capable of targeting those epitopes for use in treatment oriented clinical trials. Multiple clinical protocols have been conducted in which patients with melanoma have been treated with adoptively transferred tumor infiltrating lymphocytes (TIL), and the objective response rates in those trials were often greater than 50%. However, using current techniques, tumor reactive TIL can only be consistently generated and expanded in vitro from patients with melanoma. Thus, new strategies are needed to extend adoptive cell transfer immunotherapies to patients with prevalent histologies such as breast, renal, colon, pancreatic, and lung cancers. In order to assist investigators in the Surgery Branch to achieve the goal of extending current adoptive cell transfer protocols, the primary focus of the Antigen Targeting Core is in developing new means for isolating tumor reactive T cells and identifying tumor reactive T cell receptors (TCRs). T cells from TIL are often heterogeneous. Some recognize non-mutated self antigens expressed on multiple tumor cells from different patients. Others recognized unique mutated antigens often only expressed in the patient's autologous tumors. The Antigen Targeting Core has developed methods for isolating T cells that recognize both shared and unique mutated antigens. For shared antigens, one approach is the use of reverse immunology. Peptides from a candidate tumor associated antigen that are predicted to bind to a patient's MHC molecules are used to stimulate lymphocytes from humans or HLA transgenic mice. In some cases, the resulting T cell populations recognize tumors expressing the shared antigen in the context of the chosen MHC molecule. Tumor reactive T cell receptors (TCRs) can then be isolated and genetically introduced into previously non-reactive human T lymphocytes to confer novel tumor reactivity. These cells can then be expanded in vitro and adoptively transferred into patients with tumors that express the candidate antigen. With recent advances in whole exome and RNA sequencing technologies, unique mutations expressed in an individual patient's tumors can now be readily identified. For some of these unique mutations, reactive T cells can be isolated from TIL by sorting cells that express 41BB after stimulation with antigen presenting cells genetically modified with RNA containing the mutation or pre-loaded with peptide containing the mutation. Once these cells have been separated from the non-reactive T cells, mutation reactive TCRs can be isolated and genetically introduced into previously non-reactive human T lymphocytes to confer novel mutation reactivity. These cells can then be expanded in vitro and adoptively transferred into the autologous patient whose tumors express the unique mutations. The Antigen Targeting Core has the expertise to use all of the afore-mentioned strategies to isolate tumor reactive T cells and TCRs for use in adoptive cell transfer protocols or gene therapy clinical trials.